1. Technical Field
The present invention relates to a method and apparatus for data processing in general, and in particular to a method and apparatus for processing audio data within a data-processing system. Still more particularly, the present invention relates to a method and apparatus for providing audio sample rate conversion within a data-processing system.
2. Description of the Prior Art
Audio presentation is one of many integral features of a personal computer (PC) system equipped with multi-media options. Typically, audio presentation support is provided by means of either adding an audio add-on board (commonly known as a sound card) to a system board of the PC system or integrating similar hardware within the system board. In both cases, integrated audio codecs are usually utilized to support the audio function. The problem with integrated audio codecs is that a relatively sensitive analog circuit is integrated (or in close proximity) with a relatively noisy digital audio circuit. As a result, the quality of audio presentation is not even comparable with that of an average home stereo.
In an effort to correct this problem, a proposal and a subsequent specification known as the Audio Codec '97 (AC 97) were introduced, with the support of Intel.RTM. Corporation and virtually all other audio integrated-circuit device manufacturers such as Analog Devices, National Semiconductor, etc. According to the AC 97 specification, analog and digital audio functions in a PC system environment must be separated into two parts, namely, an analog audio codec and a digital audio controller. Moreover, interface and pinout of analog codecs are standardized in a way that an OEM can mix and match analog codecs and digital controllers from different vendors. Additionally, the analog codec is to operate only at a sample rate of 48 KHz, utilizing up to 20-bit samples.
Despite of all the advantages provided by the AC 97 specification, the rigidity of 48 KHz sample rate presents some problems when interfacing with devices having a commonly used sample rate that is not 48 KHz. Incidentally, sample rate conversions are unavoidable with an AC 97 compliance system. Thus, it is an objective of the present disclosure to describe a method and apparatus for providing audio sample rate conversion within a data-processing system having a digital audio controller that conforms to the AC 97 specification.